It is desirable to produce ethylene/α-olefin interpolymer compositions of controlled molecular weight distribution in a cost-effective manner. In particular ethylene/α-olefin interpolymer compositions having a multi-modal (two or more modes wherein the case of two may interchangeably be referred to as bimodal or multi-modal) molecular weight distribution are often desirable for some applications, for example, pipes for natural gas, sewers, mining, etc. Also, some applications may require compositions wherein a low molecular weight portion of the ethylene/α-olefin interpolymer composition has a higher density than a high molecular weight portion of the ethylene/α-olefin interpolymer composition. Unfortunately, to date the available processes do not effectively and efficiently control the distribution or result in compositions with the desired density and molecular weight combinations. Therefore, there is a need for processes that can control the molecular weight distribution or result in compositions with the desired density and molecular weight combinations. There is also a need for interpolymers having improved properties, e.g., heat seal and residual enthalpy, as well as, improved film layers and films having such properties.